I don't remember the max shutter speed on those (used to shoot a D70 myself), but its not going to be much above 1/200s, 1/300s tops. Nikon has some fancy stuff they do with their TTL flash system (essentially, they lower flash power and extend its duration) that allows for faster max sync speed (I think it goes up to about 1/320s max) when using Nikon brand flashes, but that doesn't apply to using studio strobes.

With a focal plane shutter found in an SLR camera, there are two curtains. The first one opens, exposing the film/sensor, then the second one closes to end the exposure. The definition of maximum flash sync speed is the highest shutter speed where the second curtain doesn't start to close until the first curtain is fully open. That is the highest speed at which the entire surface of the film/sensor is exposed at the same time. If the flash fires during that instant, you will expose the full surface of the film/sensor. At faster shutter speeds, what you end up with is a small slit (the gap between the opening and closing curtains) passing over the film/sensor. In that way, an amount of light equal to the desired exposure duration is allowed to pass, but the total surface of the film is never exposed to light at the same time. Since the flash can be (for all practical purposes here) thought of as taking place over an instantaneously short period of time, all that gets exposed is whatever portion of the film/sensor that happened to be open to light at the moment it is fired.

That is what is meant when people talk about leaf shutters (such as what you have with the RZ) "synchronizing at any speed". With a leaf shutter, no matter the shutter speed, there is still an instant where the entire shutter is fully open.

I shoot digital when I have to (most of those shots end up here) and film (occasionally one of those shots ends up here) when I want to.

One thing I didn't test is without flash. But if there was enough ambient light to show, wouldn't 1/4s be over exposed?
I should have also exceeded the sync speed to show that there is no ambient at that bar.

Last edited by mweintraub; 03-09-2014 at 08:20 AM. Click to view previous post history.

Well, you are definitely having sync speed issues at 250. That's not a surprise to me with off camera flash.

I think part of what is keeping you from seeing the effect of ambient here is the relatively small aperture 6.3-7.1 in this test compared to the f2.8 you were using in post 49, that's roughly 2.5 stops you've knocked off the ambient.

Mark Barendt, Beaverton, OR

"We do not see things the way they are. We see things the way we are." Anaïs Nin

I'm struggling to understand what you are doing here. There are so many variables in your tests, you're really not isolating any one thing.

It appears that your hypothesis is that shutter duration effects exposure under isolated flash lighting. It also appears to me that you are under the impression that your testing environment has such low ambient light that it can be ignored.

One thing I didn't test is without flash.

The test without the flash is the most important part.

But if there was enough ambient light to show, wouldn't 1/4s be over exposed?

The shots at 1/4s are visibly brighter. How do you interpret that?

I should have also exceeded the sync speed to show that there is no ambient at that bar.

There are six stops of difference between 1/4s and 1/250s. Even if the black bars show full shadow at 1/250s (which I doubt. I bet if you pulled the RAW file into Photoshop and cranked the exposure, you would find that there is a hint of detail there), that doesn't mean there is not enough ambient light to create meaningful exposure at 1/4s.

I shoot digital when I have to (most of those shots end up here) and film (occasionally one of those shots ends up here) when I want to.

Well, you are definitely having sync speed issues at 250. That's not a surprise to me with off camera flash.

I think part of what is keeping you from seeing the effect of ambient here is the relatively small aperture 6.3-7.1 in this test compared to the f2.8 you were using in post 49, that's roughly 2.5 stops you've knocked off the ambient.

Where did I use f/2.8? The only time I used anything other than 6.3/7.1 is to show how low the ambient

Originally Posted by omaha

I'm struggling to understand what you are doing here. There are so many variables in your tests, you're really not isolating any one thing.

There is only variable with each test type is the shutter speed. I shouldn't have put ALL the photos in one folder, sorry.

Originally Posted by omaha

It appears that your hypothesis is that shutter duration effects exposure under isolated flash lighting. It also appears to me that you are under the impression that your testing environment has such low ambient light that it can be ignored.

Yes. I would think that if in order to get a proper exposure is to go up to ISO 3200 and drop the aperture a few stops then ambient is very low.

Originally Posted by omaha

The test without the flash is the most important part.

I'll try that again tonight (with adjustment for DST).

Originally Posted by omaha

The shots at 1/4s are visibly brighter. How do you interpret that?

Visibly brighter, yes, but only slightly! 1/4s is four stops slower than 1/60 and only a minor difference to my eyes. 1/200s is two stops faster than 1/60s and makes a huge difference.

Originally Posted by omaha

There are six stops of difference between 1/4s and 1/250s. Even if the black bars show full shadow at 1/250s (which I doubt. I bet if you pulled the RAW file into Photoshop and cranked the exposure, you would find that there is a hint of detail there), that doesn't mean there is not enough ambient light to create meaningful exposure at 1/4s.

So I've moved the photos into folders for their respective tests. This isolates the shutterspeed as the only variable.

If you look at the the folder called "Lights Off, CTR-301P, Fotodiox" and "Lights Off, CTR-301P, SB600" then compare the 1/60s and 1/200s shots, you'll notice the underexposed photo from the Fotodiox. With the lights off (and having to use my phone to see anything in the room), there should be 100% no ambient light.

OK, so what do you want me to test? What am I missing? Why is the SB-600 photos at 1/200 not as dark as the Fotodiox? I'm not sure what else I can do. Maybe I need to stop trying to convince you guys. =/

What is it you are trying to compare? The flash power of the SB-600 vs the Fotodiox, or the effect of shutter duration on strobe lighting?

I go back to the test I proposed in post #57:

Originally Posted by omaha

Shoot a series of frames in that light (same f/stop as before, varying the shutter) with the RZ and see what you get.

For a proper experiment, start with a perfectly (or as nearly so as is practical...a bedroom with the door closed and the lights off in the hall and the curtains drawn at night will do) dark room.

Set up something for a subject, set up your strobe and set it so it meters f/8 at the subject. Set your RZ to f/8.

Take a series of five shots, varying the shutter from 1/4 through 1/250.

Now, add a bright table lamp to the room. Don't change anything else, and repeat the same five shots.

Unless something is gitchy about your strobe (ie, inconsistent power output), the first five should be identical, and the second five should be progressively less exposed.

In truth, you can simplify that further. Instead of a series of five shots at different shutter speeds, just shoot one shot at 1/2s and one shot at 1/200s.

You will end up with a set of four shots: Two with strobe only (assuming you find a room that is truly dark), and two with strobe + ambient.

Its not important which strobe or which triggering method you use. Just pick one of each and stick with it. Run the test, then post the four photos. Actually, I take that back. Use the Fotodiox. Nikon stuff is so "smart" there is always the risk of forgetting to turn off some automatic adjustment feature, spoiling the test.

As an aside, in any sort of indoor/studio situation where I have the time to carefully light a shot, I vastly prefer studio lights to speedlights. I only use speedlights when I am either taking a bunch of candid shots indoors (such as shooting a party, where I'll set a couple of speedlights in strategic locations in the room, bounce the light off the ceiling, and slave them wirelessly to the camera using Nikon's uber-smart TTL metering) or need fill flash outdoors in a spot where power is not readily available.

I shoot digital when I have to (most of those shots end up here) and film (occasionally one of those shots ends up here) when I want to.